As you can clearly see from my results, the wave direction and wind direction are exactly the same. This is correct because as we know, the wave direction is affected by the wind direction.
Aim 2c
The purpose of the aim is to see whether Longshore Drift is taking place on the day of our visit and if so, in what direction.
Longshore Drift
Longshore drift is the movement of material along the shore by wave action.
Longshore drift happens when waves moves towards the coast at an angle. The swash (waves moving up the beach) carries material up and along the beach. The backwash carries material back down the beach at right angles. This is the result of gravity. This process slowly moves material along the beach.
Longshore drift provides a link between erosion and deposition. Material in one place is eroded, transported then deposited elsewhere.
Longshore Drift moves material along a coastline. Where there is an obstruction or the power of the waves is reduced the material is deposited. Where rivers or estuaries meet the sea deposition often occurs. The sediment which is deposited usually builds up over the years to form a long ridge of material (usually sand or shingle). Such a ridge is called a spit. Spurn Head on the Holderness Coast is an example of this feature. The general direction of longshore drift around the coasts of the British Isles is controlled by the direction of the dominant wind. Prevailing westerly winds cause the drift from the west to east along the Channel coast and south to north along the west coast. The east coast is protected by land from the prevailing south-westerly winds. However, winds from the north cause longshore drift movement from north to south on the east coast. Northerly winds (winds from the north) have crossed a long stretch of open sea so that, although they do not blow as frequently as the westerly winds, they have the greatest influence overall. Longshore drift is important in the formation of all landforms of coastal deposition.
Methodology
First we measured any longshore drift taking place on the surface of the water by floating a piece of driftwood in the sea surface. We put a ranging pole beside the water’s edge at the point opposite where we threw our floating piece of wood (about 30cm x 30cm x 3cm) into the sea. The wood wasn’t too high because then it sticks out of the water and would be caught by the wind. Wind aiding the movement of the wood would not be a true reflection of surface longshore drift.
After each minute we plotted the distance it had travelled along the shore in the sea by using measuring tape from the ranging pole along the beach. We needed to assess before we laid out our measuring tape, in which direction the longshore drift was taking place so we knew which side of the ranging pole to lay out our tape.
To measure any longshore drift on the sea bed on the day of our visit, we threw our 30 coloured pebbles into the swash of the wave by the shore. We marked the point with a
ranging pole on the beach. After 5 minute intervals we measured the distance they travelled from the ranging pole.
This fieldwork method was chosen as it seemed to be the easiest and most practical way to collect our data on longshore drift.
Limitations
My group was the group right next to the pier. We found that the pier affected the angle of which the waves approached the beach, which interrupted longshore drift.
Most of our pebbles disappeared because the backwash was too strong because the waves were destructive (see aim1 table and graph) because the wind that day was at an average of 6.4mph.
The stones collected could have been too large or too small and angular to roll along the seabed. Selecting the correct place within the swash to get maximum movement was difficult.
Finally, the plank of wood could have been too tall (caught by the wind and so did not truly measure Longshore Drift as it was wind assisted).
Results
Wind Speed:
By looking at the limitation section I wrote about earlier, as we were right next to the pier, our results for the seabed and surface longshore drift were incorrect, so we used somebody else’s results.
Surface Longshore Drift
Seabed Longshore Drift
Analyse
By looking at all the results I collected for wind speed, it is clear to see that there was an average of about 6.4. As we were by the pier, I had to use somebody else’s results, for the surface and seabed longshore drift. For the seabed longshore drift (pebbles) there is a clear increase of about 7 or 8 cm every 5 minutes. The results for the surface longshore drift show a much wider range of results.
Conclusion
I can conclude from my results that it is clear to see that longshore drift is taking place and we did manage to find the direction of the wind and the longshore drift. The wind was affective on the day of our visit, because it did direct the waves in the same direction of itself, as the results of the wind and wave direction showed.
Relation to hypothesis
After concluding my results, I found that on the day of our visit, longshore drift was taking place, and the direction of which was south easterly. My hypothesis is ‘to see if Deal is being shaped more due to the process of L.D (if we found L.D present on our visit) or by human activity on the beach’. My results do show that the beach is being shaped by longshore drift because longshore drift was taking place on the day of our visit.